1. Field of the Invention
The present invention relates to an image capture apparatus and a method of controlling the same.
2. Description of the Related Art
Conventionally, video cameras and still cameras have differed in many respects. The former apparatuses have been apparatuses designed to capture only moving images, whereas the latter apparatuses have been apparatuses designed to capture only still images. However, both the types of apparatuses have started using image sensors and have digitally processed images. This has been reducing the differences between them. Recently, the still image shooting function of a video camera and the movie shooting function of a still camera have greatly advanced from the initial levels to such an extent that even a compact still camera like that built in a cellular phone can perform movie shooting with a full HD (high definition) resolution.
Recently, in particular, since a digital still camera with interchangeable lenses has also been equipped with a movie shooting function, movie shooting by the still camera has attracted a great deal of attention. This may be because a digital still camera with interchangeable lenses uses a large-sized image sensor with a large number of pixels, interchanging lenses facilitates changing the angle of view, and allows still image shooting with high image quality.
When performing shooting operation premised on being subjected to editing as in the case of movies and television, the apparatus performs recording with importance being attached to tone gradation to minimize blown-out highlights and blocked-up shadows so as to ensure an adjustable range at the time of editing. More specifically, it is known that recording is performed by using nonlinear input-output characteristics (called Log gamma) that exhibit a logarithmic increase with an increase in luminance value. Such nonlinear input-output characteristics are called Log or Log gamma and defined as a function or table. In addition, further converting film scan data, converted by the defined Log gamma, by using Cineon LOG or the like proposed for film scan data recording proposed by Kodak, U.S.A. allows the data to be handled as image data similar in characteristic to the photosensitivity of a photograph film. Using Log gamma can maintain high tone gradation by suppressing blown-out highlights and blocked-up shadows. However, the recorded moving image becomes a low-contrast image, with a dark portion becoming brighter and a bright portion becoming darker. For this reason, this image is not suitable for appreciation without any change, and hence needs to be converted into linear tone characteristics with respect to human visual features in the end.
In television or movie production, moving images having Log gamma characteristics are generally edited. Conventionally, however, the movie shooting function of a digital still camera is designed to record moving images converted into images having tone characteristics or contrast suitable for appreciation without any editing processing after shooting operation (to be referred to as postproduction processing). For this reason, digital still cameras have also been required to support movie recording using Log gamma.
However, problems arise when the movie shooting function of a digital still camera is configured to allow the application of Log gamma. Although having the movie shooting function, the digital still camera is still an apparatus mainly designed for still image recording. Unlike moving images, still images each are obtained by capturing a moment and are appreciated on a screen or in the form of a print. For this reason, various types of image correction functions for image formation are prepared to obtain shooting results reflecting the intentions of a photographer.
As a typical image correction function, there is available a function of performing the processing of converting image characteristics such as hue and saturation with image processing parameters in accordance with a shooting scene (Japanese Patent Laid-Open No. 2008-245246). For example, color correction is performed to, for example, obtain results similar to memory colors by enhancing the reddish color of a sunset in an evening scene and enhancing the vividness of blue and green in a landscape scene, and obtain a healthy skin color in a portrait. It is also known that automatic tone correction is performed in accordance with the luminance of an image in a shooting scene (Japanese Patent Laid-Open No. 2010-39758).
These image correction functions influence the tone characteristics or contrast of an image (change the tone characteristics or contrast). In addition, the circuit for performing image processing is common to still images and moving images, and hence the image correction functions are also applied to moving images. However, these image correction functions should not be applied to moving images shot by applying Log gamma. This is because an apparatus designed to perform editing processing after shooting (to be referred to as postproduction processing) is premised on the input of images having the Log gamma characteristics defined on the camera side. When, however, receiving an image having undergone the above image correction, the apparatus handles the image having unexpected characteristics. This may cause degradation in the image quality of the edited image.